As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIT-BWI - FLT 276 - DURING CLIMB-OUT, THERE WAS A BURNING SMELL IN THE PASSENGER CABIN, BUT NO VISIBLE SMOKE. THE FLIGHT RETURNED TO THE FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE RE-CIRCULATING FAN FILTER. RAN ENGINES AND AIR CONDITIONING PACKS. ALL CHECKED NORMAL. (M)